Conventionally, when a heat sink is attached for cooling electronic components (power semiconductor elements) that generate a large amount of heat such as a CPU (central processing unit) and a power transistor, application of thermal grease is widely performed to fill a minute gap between a contact surface of the electronic components and that of the heat sink to improve heat dissipation performance.
The thermal conductivity of the thermal grease is quite lower than those of metals. Accordingly, a radiation-fin-integrated power semiconductor device having radiation fins integrated with a base plate of a metallic part of the power semiconductor device without using the thermal grease is also realized to further improve the heat dissipation performance. In the radiation-fin-integrated power semiconductor device, grooves for joining the radiation fins are provided in the base plate, resin molding is performed in a state of exposing a part of the surface of the base plate including a portion in which these grooves are formed, and the radiation fins are inserted into the grooves of the base plate and then swaged to be fixedly attached to the grooves, thereby integrating the base plate with the radiation fins to improve the heat dissipation performance.
In relation to the power semiconductor device adapted to improve the heat dissipation performance, it is known that radiation noise from power semiconductor elements and malfunction is suppressed by inserting a metal plate between the radiation fins and the base plate and by causing this metal plate to function to connect the power semiconductor device to an earth potential (see Patent Literature 1).